TT electronics has introduced a comprehensive range of wirewound resistors offering the industry’s highest surge energy ratings from 2W to 7W sizes. Suitable for a wide range of pulse applications, the WHS series flameproof resistor is aimed particularly at designers of power supplies requiring a line input resistor for inrush limiting and protection.
Optimized surge performance derives from the special winding design of these resistors, in which a high-purity ceramic substrate is assembled with interference fit end-caps welded to the terminations. The resistive element is then wound on the substrate and welded to the caps. Its ability to withstand the high surge conditions associated with switch-on, discharge or external surge events results in improved reliability, savings in PCB space and reduced need for additional components.
The WHS2, rated at 2W, is the smallest resistor of its type on the market and provides surge energy ratings of 0.9 to 5.8J. Models are available rated 3, 5 and 7W, in resistance values up to 330Ω and taking energy ratings up to 60J. With a 10W model under development, the WHS family will offer better performance than competitors over a wider span of power and resistance. Moreover, designers have greater flexibility with the additional options of radial, goalpost, lancet and SMD Z-form leads. All the new resistors benefit from UL94-V0 flameproof protection and operate over a wide -55o to +155°C temperature range. Delivered in tape-and-reel format as standard, they are RoHS compliant with lead-free terminations.